Memory Cell And An Array Of Memory Cells

ABSTRACT

A memory cell includes a first electrode and a second electrode. A select device and a programmable device are in series with each other between the first and second electrodes. The select device is proximate and electrically coupled to the first electrode. The programmable device is proximate and electrically coupled to the second electrode. The programmable device includes a radially inner electrode having radially outer sidewalls. Ferroelectric material is radially outward of the outer sidewalls of the inner electrode. A radially outer electrode is radially outward of the ferroelectric material. One of the outer electrode or the inner electrode is electrically coupled to the select device. The other of the outer electrode and the inner electrode is electrically coupled to the second electrode. Arrays of memory cells are disclosed.

This patent resulted from a divisional application of U.S. patentapplication Ser. No. 16/007,054, filed Jun. 13, 2018, entitled “MemoryCell And An Array Of Memory Cells”, naming Durai Vishak NirmalRamaswamy, Wayne Kinney, and Marco Domenico Tiburzi as inventors, whichwas a continuation application of U.S. patent application Ser. No.15/275,895, filed Sep. 26, 2016, entitled “Memory Cell And An Array OfMemory Cells”, naming Durai Vishak Nirmal Ramaswamy, Wayne Kinney, andMarco Domenico Tiburzi as inventors, now U.S. Pat. No. 10,074,662, whichwas a continuation application of U.S. patent application Ser. No.14/305,459, filed Jun. 16, 2014, entitled “Memory Cell And An Array OfMemory Cells”, naming Durai Vishak Nirmal Ramaswamy, Wayne Kinney, andMarco Domenico Tiburzi as inventors, now U.S. Pat. No. 9,472,560, thedisclosures of which are incorporated by reference.

TECHNICAL FIELD

Embodiments disclosed herein pertain to memory cells and to arrays ofmemory cells.

BACKGROUND

Memory is one type of integrated circuitry, and is used in computersystems for storing data. Integrated memory is usually fabricated in oneor more arrays of individual memory cells. The memory cells areconfigured to retain or store memory in at least two differentselectable states. In a binary system, the states are considered aseither a “0” or a “1”. In other systems, at least some individual memorycells may be configured to store more than two levels or states ofinformation. The memory cells might be volatile, semi-volatile, ornonvolatile. Nonvolatile memory cells can store data for extendedperiods of time in the absence of power. Nonvolatile memory isconventionally specified to be memory having a retention time of atleast about 10 years. Volatile memory dissipates, and is thereforerefreshed/rewritten to maintain data storage. Volatile memory may have aretention time of milliseconds, or less.

Integrated circuitry fabrication continues to strive to produce smallerand denser integrated circuits. There is a continuing effort to reducethe number of components in individual devices because such can reducethe size of finished constructions and simplify processing. The smallestand simplest memory cell will likely be comprised of two electrodeshaving a programmable material, and possibly a select device (such as adiode or ovonic threshold switch), received between them. Suitableprogrammable materials have two or more selectable memory states toenable storing of information by an individual memory cell. The readingof the cell comprises determination of which of the states theprogrammable material is in, and the writing of information to the cellcomprises placing the programmable material in a predetermined state.Some programmable materials retain a memory state in the absence ofrefresh, and thus may be incorporated into nonvolatile memory cells.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagrammatic perspective view of a portion of a memory arrayin accordance with an embodiment of the invention.

FIG. 1A is an enlargement of a portion of FIG. 1, including a cutawayportion.

FIG. 2 is a vertical cross section taken along a longitudinal or axialcenter of one of the memory cells in the array of FIG. 1.

FIG. 3 is a horizontal cross section taken through line 3-3 in FIG. 2.

FIG. 4 is a vertical cross section taken along a longitudinal or axialcenter of an alternate embodiment memory cell.

FIG. 5 is a vertical cross section taken along a longitudinal or axialcenter of an alternate embodiment memory cell.

FIG. 6 is a diagrammatic perspective view of a portion of an alternatememory array in accordance with an embodiment of the invention.

FIG. 6A is an enlargement of a portion of FIG. 6, including a cutawayportion.

FIG. 7 is a vertical cross section taken along a longitudinal or axialcenter of one of the memory cells in the array of FIG. 6.

FIG. 8 is a horizontal cross section taken through line 8-8 in FIG. 7.

FIG. 9 is a vertical cross section taken along a longitudinal or axialcenter of an alternate embodiment memory cell.

FIG. 10 is a vertical cross section taken along a longitudinal or axialcenter of an alternate embodiment memory cell.

FIG. 11 is a vertical cross section taken along a longitudinal or axialcenter of an alternate embodiment memory cell.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS

Embodiments of the invention encompass a memory cell and an array ofmemory cells. FIG. 1 shows a portion of a substrate constructioncomprising an array 10 of individual memory cells 12 that has beenfabricated relative to a base substrate 11. Only four memory cells 12are shown, with an array of such memory cells likely including thousandsor millions of individual memory cells. FIGS. 1 and 1A are diagrammaticdepicting operative portions of the memory cells and conductive linesthat form a part thereof and/or to which such connect. Solid dielectricmaterial would likely be received entirely about the depictedconstruction, but is not shown in the figures for clarity with respectto operative components. Substrate 11 may comprise a semiconductorsubstrate. In the context of this document, the term “semiconductorsubstrate” or “semiconductive substrate” is defined to mean anyconstruction comprising semiconductive material, including, but notlimited to, bulk semiconductive materials such as a semiconductive wafer(either alone or in assemblies comprising other materials thereon), andsemiconductive material layers (either alone or in assemblies comprisingother materials). The term “substrate” refers to any supportingstructure, including, but not limited to, the semiconductive substratesdescribed above. Partially or wholly fabricated components of integratedcircuitry may be formed as part of, or be elevationally inward of,substrate material 11.

Any of the materials and/or structures described herein may behomogenous or non-homogenous, and regardless may be continuous ordiscontinuous over any material that such overlie. As used herein,“different composition” only requires those portions of two statedmaterials that may be directly against one another to be chemicallyand/or physically different, for example if such materials are nothomogenous. If the two stated materials are not directly against oneanother, “different composition” only requires that those portions ofthe two stated materials that are closest to one another be chemicallyand/or physically different if such materials are not homogenous. Inthis document, a material or structure is “directly against” anotherwhen there is at least some physical touching contact of the statedmaterials or structures relative one another. In contrast, “over”, “on”,and “against” not preceded by “directly”, encompass “directly against”as well as construction where intervening material(s) or structure(s)result(s) in no physical touching contact of the stated materials orstructures relative one another. Further, unless otherwise stated, eachmaterial may be formed using any suitable existing oryet-to-be-developed technique, with atomic layer deposition, chemicalvapor deposition, physical vapor deposition, epitaxial growth, diffusiondoping, and ion implanting being examples.

Array 10 comprises spaced first lines 14, spaced second lines 16 whichcross first lines 14, and an individual memory cell 12 between firstlines 14 and second lines 16 where such cross. Reference to “first” and“second” with respect to different components herein is only forconvenience in description in referring to different components.Accordingly, “first” and “second” may be interchanged independent ofrelative position within the finished circuit construction andindependent of sequence in fabrication. Lines 14 and 16 compriseconductive (i.e., electrically) material, with examples being elementalmetals, a mixture or alloy of two or more elemental metals, conductivemetal compounds, and conductively-doped semiconductive materials. Lines14 and 16 may be of the same composition or of different compositionsrelative one another.

Referring to FIGS. 1, 1A, 2, and 3, the discussion proceeds withreference to an individual memory cell 12, with each of memory cells 12in an individual memory array likely being of the same essentialconstruction relative one another. Memory cell 12 comprises a firstelectrode 14 (e.g., at least a portion of a first line 14) and a secondelectrode 16 (e.g., at least a portion of a second line 16). Memory cell12 also comprises a select device 18 and a programmable device 20 whichare in series (i.e., electrical connection) with each other betweenfirst electrode 14 and second electrode 16. The select device isproximate to (e.g., more so than is the programmable device) andelectrically coupled to the first electrode. The programmable device isproximate to (e.g., more so than is the select device) and electricallycoupled to the second electrode. Again, use of “first” and “second” isfor convenience only and the second electrode may be considered as thefirst electrode while the first electrode may considered as the secondelectrode. Additionally or regardless, the select device may beproximate and electrically coupled to the second electrode and theprogrammable device may be proximate and electrically coupled to thefirst electrode. Examples for each are shown and described herein. Inthe context of this document, devices or components are electricallycoupled relative one another if in normal operation electric current iscapable of continuously flowing from one to the other, and does sopredominately by movement of subatomic positive and/or negative chargeswhen such are sufficiently generated as opposed to predominately bymovement of ions.

FIGS. 1-3 show an example embodiment wherein select device 18 isproximate and electrically coupled to first electrode 14 andprogrammable device 20 is proximate and electrically coupled to secondelectrode 16. Additionally, and in one embodiment, FIGS. 1-3 show anexample wherein first electrode 14 comprises an upper electrode, andsecond electrode 16 comprises a lower electrode. In this document,“upper”, “lower”, “elevational”, “top”, and “bottom” are with referenceto the vertical direction. “Horizontal” refers to a general directionalong a primary surface relative to which the substrate is processedduring fabrication, and vertical is a direction generally orthogonalthereto. Further, “vertical” and “horizontal” as used herein aregenerally perpendicular directions relative one another and independentof orientation of the substrate in three-dimensional space. In oneembodiment and as shown, no intervening circuit component is betweenselect device 18 and first electrode 14. In one embodiment and as shown,no intervening circuit component is between programmable device 20 andsecond electrode 16. In one embodiment and as shown, select device 18 isdirectly against first electrode 14. In one embodiment and as shown,programmable device 20 is directly against second electrode 16.

Select device 18 may be formed of any suitable material(s) to provide aselect device function. Examples include a tunnel junction device and adiode. Example diodes include PN diodes, PIN diodes, Schottky diodes,Zener diodes, avalanche diodes, tunnel diodes, diodes having more thanthree different materials, etc. As additional examples, select device 18may be a junction field effect or bipolar transistor. In one embodiment,select device 18 comprises a metal-semiconductor-metal diodeconstruction. Example metals include elemental form metals, alloys oftwo or more elemental metals, and conductive metal compounds. Examplesemiconductor materials include silicon, for example amorphous,monocrystalline, and polycrystalline silicon which may be doped with aconductivity modifying impurity. Example thicknesses for the metal,semiconductor, metal in such a construction is about 100 to 150Angstroms, 50 to 500 Angstroms, and 100 to 150 Angstroms, respectively.In this document, “thickness” by itself (no preceding directionaladjective) is defined as the mean straight-line distance through a givenmaterial or region perpendicularly from a closest surface of animmediately adjacent material of different composition or of animmediately adjacent region. Additionally, the various materialsdescribed herein may be of substantially constant thickness or ofvariable thicknesses. If of variable thickness, thickness refers toaverage thickness.

Programmable device 20 comprises a radially inner electrode 22 havingradially outer sidewalls 24. In one embodiment and as shown, innerelectrode 22 is of a solid pillar shape in a vertical cross-sectiontaken through an axial center of inner electrode 22 (e.g., a verticalcross-section which is FIG. 2), and in one embodiment is directlyagainst select device 18. Example materials for electrode 22 include anyof those described above for lines 14 and 16. Ferroelectric material 26has been formed radially outward of the outer sidewalls of innerelectrode 22, and in one embodiment is directly against inner electrode22. Any suitable existing or yet-to-be-developed ferroelectric materialmay be used. Examples include ferroelectrics that have one or more oftransition metal oxide, zirconium, zirconium oxide, hafnium, hafniumoxide, lead zirconium titanate, and barium strontium titanate, and mayhave dopant therein which comprises one or more of silicon, aluminum,lanthanum, yttrium, erbium, calcium, magnesium, strontium, and a rareearth element. Two specific examples are Hf_(x)Si_(y)O_(z) (e.g.,including hafnium oxide doped with silicon dioxide) andHf_(x)Zr_(y)O_(z). An example thickness for ferroelectric material 26 isabout 30 to 100 Angstroms. In one embodiment and as shown, ferroelectricmaterial 26 circumferentially surrounds inner electrode 22 in at leastone horizontal cross-section (e.g., a horizontal cross-section which isFIG. 3).

A radially outer electrode 28 is radially outward of ferroelectricmaterial 26, and in one embodiment is directly against material 26.Example materials include any of those described above for innerelectrode 22. Electrodes 22 and 28 may be of the same composition or ofdifferent compositions relative one another. An example thickness forouter electrode 28 is about 30 to 100 Angstroms. In one embodiment andas shown, outer electrode 28 completely circumferentially surroundsferroelectric material 26 in at least one horizontal cross-section(e.g., that of FIG. 3). In one embodiment and as shown, outer electrode28 is of an upwardly open container-like shape in a verticalcross-section taken through an axial center of outer electrode 28 (e.g.,that of FIG. 2).

One of the outer electrode or the inner electrode is electricallycoupled to the select device with the other being electrically coupledto the second electrode. FIGS. 1-3 depict an example embodiment whereinouter electrode 28 is electrically coupled to second electrode 16 andinner electrode 22 is electrically coupled to select device 18. In oneembodiment, inner electrode 22 is directly against select device 18, andin one embodiment select device 18 is directly against first electrode14. In one embodiment, outer electrode 28 is directly against secondelectrode 16.

FIGS. 1-3 show programmable device 20 as tapering radially inward movingelevationally inward towards base substrate 11 (FIG. 1), likely anartifact of manufacture. Alternately as examples, components ofprogrammable device 20 may have vertical sidewalls or taper radiallyoutward. An example elevational thickness for programmable device 20 isabout 0.1 micron to 1.5 microns.

FIG. 4 shows an alternate example embodiment memory cell 12 a. Likenumerals from the above-described embodiments have been used whereappropriate, with some construction differences being indicated with thesuffix “a” or with different numerals. Inner electrode 22 a ofprogrammable device 20 a is of an upwardly open container-like shape ina vertical cross-section taken through an axial center of innerelectrode 22 a. A dielectric material 30 has been formed there-within.Example dielectric materials are silicon nitride and doped or undopedsilicon dioxide.

An alternate memory cell 12 b in accordance with an embodiment of theinvention is shown in FIG. 5. Like numerals from the above-describedembodiments have been used where appropriate, with some constructiondifferences being indicated with the suffix “b” or with differentnumerals. FIG. 5 shows a memory cell 12 b wherein programmable device 20b has outer electrode 28 b electrically coupled to select device 18 andinner electrode 22 b electrically coupled to second electrode 16. In oneembodiment and as shown, ferroelectric material 26 b is of an upwardlyopen and downwardly open cylinder-like shape in a vertical cross-sectiontaken through an axial center of ferroelectric material 26 b (e.g., thevertical cross-section shown by FIG. 5). In one embodiment and as shown,outer electrode 28 b is of an upwardly open and downwardly opencylinder-like shape in a vertical cross-section taken through an axialcenter of the outer electrode. As an alternate or additional example,inner electrode 22 b may be fabricated of an upwardly opencontainer-like shape (not shown) analogous to that shown for innerelectrode 22 a in FIG. 4. A dielectric 34 electrically isolates innerelectrode 22 b from select device 18. Example dielectric materials areany of those described above for dielectric material 30.

Example additional embodiments in accordance with the invention are nextdescribed with reference to FIGS. 6-11 wherein the select device isproximate to and electrically couples to the second or lower electrodeand the programmable device is proximate to and electrically couples tothe first or upper electrode. Referring to FIGS. 6-8, an alternateembodiment memory cell 12 c is shown. Like numerals from theabove-described embodiments have been used where appropriate, with someconstruction differences being indicated with the suffix “c” or withdifferent numerals. FIGS. 6-8 show an embodiment largely analogous tothat of FIGS. 1-3 however wherein select device 18 is between outerelectrode 28 and second electrode 16 and inner electrode 22 electricallycouples to first electrode 14. In one embodiment, inner electrode 22 isdirectly against first electrode 14. In one embodiment, outer electrode28 is directly against select device 18, and in one embodiment selectdevice 18 is directly against second electrode 16.

The ferroelectric material may be directly against one (i.e., at leastone) of the first and second electrodes, may be directly against onlyone of the first and second electrodes, or may not be directly againsteither of the first and second electrodes. FIGS. 1-5 show exampleembodiments wherein the ferroelectric material is not directly againsteither of electrodes 14 and 16. Alternately as examples, ferroelectricmaterial 26 in the FIGS. 1-4 embodiments may extend to be directlyagainst (not shown) first electrode 14 (e.g., including to extendlongitudinally there-along). In the FIG. 5 embodiment, ferroelectricmaterial 26 b may extend to be directly against (not shown) secondelectrode 16 (e.g., including to extend longitudinally there-along). Inthe FIGS. 6-8 embodiment, ferroelectric material 26 extends to bedirectly against first electrode 14 and to extend longitudinallythere-along. As alternate examples, ferroelectric material 26 may bedirectly against but not extend longitudinally along (not shown) firstelectrode 14, or not be directly against (not shown) first electrode 14.

An alternate memory cell 12 d in accordance with an embodiment of theinvention is shown in FIG. 9. Like numerals from the above-describedembodiments have been used where appropriate, with some constructiondifferences being indicated with the suffix “d” or with differentnumerals. Memory cell construction 12 d is analogous to that of FIG. 4,except wherein outer electrode 28 d of programmable device 20 delectrically couples (e.g., directly in the absence of any interveningcircuit component) to select device 18 and inner electrode 22 delectrically couples (e.g., directly in the absence of any interveningcircuit component) to first electrode 14. Inner electrode 22 d ofprogrammable device 20 d is of an upwardly open container-like shape ina vertical cross-section taken through an axial center of innerelectrode 22 d.

An alternate memory cell 12 e in accordance with an embodiment of theinvention is shown in FIG. 10. Like numerals from the above-describedembodiments have been used where appropriate, with some constructiondifferences being indicated with the suffix “e” or with differentnumerals. Memory cell construction 12 e is analogous to that of FIG. 5,except wherein inner electrode 22 e of programmable device 20 eelectrically couples (e.g., directly in the absence of any interveningcircuit component) to select device 18 and outer electrode 28 eelectrically couples (e.g., directly in the absence of any interveningcircuit component) to first electrode 14. Inner electrode 22 e ofprogrammable device 20 e is of a solid pillar shape in a verticalcross-section taken through an axial center of inner electrode 22 e.Ferroelectric material 26 e is of an upwardly open and downwardly opencylinder-like shape in a vertical cross-section taken through an axialcenter of ferroelectric material 26. Outer electrode 28 e is of anupwardly open and downwardly open cylinder-like shape in a verticalcross-section taken through an axial center of the outer electrode.

An alternate memory cell 12 f in accordance with an embodiment of theinvention is shown in FIG. 11. Like numerals from the above-describedembodiments have been used where appropriate, with some constructiondifferences being indicated with the suffix “f” or with differentnumerals. Memory cell construction 12 f is analogous to that of FIG. 10,except wherein inner electrode 22 f is not of a solid pillar shape butrather of an upwardly open container-like shape.

CONCLUSION

In some embodiments, a memory cell comprises a first electrode and asecond electrode. A select device and a programmable device are inseries with each other between the first and second electrodes. Theselect device is proximate and electrically coupled to the firstelectrode. The programmable device is proximate and electrically coupledto the second electrode. The programmable device comprises a radiallyinner electrode having radially outer sidewalls. Ferroelectric materialis radially outward of the outer sidewalls of the inner electrode. Aradially outer electrode is radially outward of the ferroelectricmaterial. One of the outer electrode or the inner electrode iselectrically coupled to the select device. The other of the outerelectrode and the inner electrode is electrically coupled to the secondelectrode.

In some embodiments, a memory cell comprises an upper electrode and alower electrode. A select device and a programmable device are in serieswith each other between the upper and lower electrodes. The selectdevice is proximate and electrically coupled to the upper electrode. Theprogrammable device is proximate and electrically coupled to the lowerelectrode. The programmable device comprises a radially inner electrodehaving radially outer sidewalls. The inner electrode is of a solidpillar shape in a vertical cross section taken through an axial centerof the inner electrode. Ferroelectric material is radially outward ofthe outer sidewalls of the inner electrode. The ferroelectric materialis of an upwardly open container-like shape in a vertical cross sectiontaken through an axial center of the ferroelectric material. A radiallyouter electrode is radially outward of the ferroelectric material. Theouter electrode is of an upwardly open container-like shape in avertical cross section taken through an axial center of the outerelectrode. The inner electrode of pillar shape is electrically coupledto the select device. The outer electrode of container-like shape iselectrically coupled to the lower electrode.

In some embodiments, a memory cell comprises an upper electrode and alower electrode. A select device and a programmable device are in serieswith each other between the upper and lower electrodes. The selectdevice is proximate and electrically coupled to the upper electrode. Theprogrammable device is proximate and electrically coupled to the lowerelectrode. The programmable device comprises a radially inner electrodehaving radially outer sidewalls. The inner electrode is of a solidpillar shape in a vertical cross section taken through an axial centerof the inner electrode. Ferroelectric material is radially outward ofthe outer sidewalls of the inner electrode. The ferroelectric materialis of an upwardly open container-like shape in a vertical cross sectiontaken through an axial center of the ferroelectric material. A radiallyouter electrode is radially outward of the ferroelectric material. Theouter electrode is of an upwardly open container-like shape in avertical cross section taken through an axial center of the outerelectrode. The inner electrode of pillar shape is electrically coupledto the select device. The outer electrode of container-like shape iselectrically coupled to the lower electrode.

In some embodiments, an array of memory cells comprises spaced firstlines, spaced second lines which cross the first lines, and anindividual memory cell between the first lines and the second lineswhere such cross. The individual memory cells comprise a select deviceand a programmable device in series with each other. The select deviceis proximate and electrically coupled to the crossing first line. Theprogrammable device is proximate and electrically coupled to thecrossing second line. The programmable device comprises a radially innerelectrode having radially outer sidewalls. Ferroelectric material isradially outward of the outer sidewalls of the inner electrode. Aradially outer electrode is radially outward of the ferroelectricmaterial. One of the outer electrode or the inner electrode iselectrically coupled to the select device. The other of the outerelectrode and the inner electrode is electrically coupled to thecrossing second line.

In compliance with the statute, the subject matter disclosed herein hasbeen described in language more or less specific as to structural andmethodical features. It is to be understood, however, that the claimsare not limited to the specific features shown and described, since themeans herein disclosed comprise example embodiments. The claims are thusto be afforded full scope as literally worded, and to be appropriatelyinterpreted in accordance with the doctrine of equivalents.

1-24. (canceled)
 25. A memory cell, comprising: a first upper electrodeand a second lower electrode; a select device and a programmable devicein series with each other between the first and second electrodes, theselect device being directly electrically coupled to the second lowerelectrode, the programmable device being directly electrically coupledto the first upper electrode; and the programmable device comprising: aradially inner electrode having radially outer sidewalls; ferroelectricmaterial radially outward of the radially outer sidewalls of theradially inner electrode; a radially outer electrode radially outward ofthe ferroelectric material; and the radially inner electrode beingdirectly electrically coupled to the first upper electrode.
 26. Thememory cell of claim 25 wherein the first upper electrode comprises onehorizontally elongated line and the second lower electrode comprisesanother horizontally elongated line.
 27. A memory cell, comprising: afirst upper electrode and a second lower electrode; a select device anda programmable device in series with each other between the first andsecond electrodes, the select device being directly electrically coupledto the second lower electrode, the programmable device being directlyelectrically coupled to the first upper electrode; and the programmabledevice comprising: a radially inner electrode having radially outersidewalls; ferroelectric material radially outward of the radially outersidewalls of the radially inner electrode; a radially outer electroderadially outward of the ferroelectric material; and the first upperelectrode comprising a horizontally elongated line, the ferroelectricmaterial being directly against and extending along an underside of thehorizontally elongated line radially outward of the radially outerelectrode.
 28. A memory cell, comprising: a first upper electrode and asecond lower electrode; a select device and a programmable device inseries with each other between the first and second electrodes, theselect device being directly electrically coupled to the second lowerelectrode, the programmable device being directly electrically coupledto the first upper electrode; and the programmable device comprising: aradially inner electrode having radially outer sidewalls; ferroelectricmaterial radially outward of the radially outer sidewalls of theradially inner electrode; a radially outer electrode radially outward ofthe ferroelectric material; and the first upper electrode comprising ahorizontally elongated line, the radially outer electrode directlyelectrically coupling with the horizontally elongated line, dielectricmaterial elevationally between and directly against the radially innerelectrode and an underside of the horizontally elongated line.
 29. Thememory cell of claim 28 wherein the dielectric material is alsoelevationally between the ferroelectric material and the underside ofthe horizontally elongated line.
 30. The memory cell of claim 29 whereinthe dielectric material is directly against an elevationally outermostsurface of the ferroelectric material.
 31. A memory cell, comprising: afirst upper electrode and a second lower electrode; a select device anda programmable device in series with each other between the first andsecond electrodes, the select device being directly electrically coupledto the lower second electrode, the programmable device being directlyelectrically coupled to the upper first electrode; and the programmabledevice comprising: a radially inner electrode having radially outersidewalls and having an upwardly open cylinder-like shape in a verticalcross section taken through an axial center of the radially innerelectrode; ferroelectric material radially outward of the radially outersidewalls of the radially inner electrode; a radially outer electroderadially outward of the ferroelectric material and directly electricallycoupled to the first upper electrode; and dielectric material radiallywithin the upwardly open cylinder-like shape of the radially innerelectrode, the dielectric material extending elevationally upward of theradially inner electrode and elevationally over tops of the radiallyinner electrode in the vertical cross section.
 32. The memory cell ofclaim 31 wherein the dielectric material is directly against said tops.33. The memory cell of claim 31 wherein the dielectric material is alsoelevationally over tops of the ferroelectric material in the verticalcross section.
 34. The memory cell of claim 33 wherein the dielectricmaterial is directly against said tops of the radially inner electrodeand directly against said tops of the ferroelectric material.